CA2377347A1 - Cementing spacers for improved well cementation - Google Patents
Cementing spacers for improved well cementation Download PDFInfo
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- CA2377347A1 CA2377347A1 CA 2377347 CA2377347A CA2377347A1 CA 2377347 A1 CA2377347 A1 CA 2377347A1 CA 2377347 CA2377347 CA 2377347 CA 2377347 A CA2377347 A CA 2377347A CA 2377347 A1 CA2377347 A1 CA 2377347A1
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- cementing
- well
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- fluid
- weighting agent
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Abstract
A method of cementing a well using a cementing spacer. The method includes pumping a drilling fluid into a well. A cementing spacer is then pumped into the well to serve as a buffer between the drilling fluid and a cement. The cementing spacer includes substantially unviscosified water and a weighting agent. Cement is then pumped into the well to displace the cementing spacer and the drilling fluid to complete the cementing of the well.
Description
PATEtaT APkLICAT10N
AT'I~RNEY bQ~XET ISO. C~h9B21Od2001 ~ s~A~E~s ~o~ m~:ov~~ vvE~~;
C~MENTA~'It7N
Cross-referet~~e to related applications This application is a continuation-in-part of U.S. Patent Application No.
Q9la~t,Q$3 led an February 26, X99$.
Background of invention Field of the Invention [UUDi] 'The invention relates generally to cementing spacers far use irr cementing wellb s. Mare specifically, the invention relates to the ><lse of Stokes haw cue ting spacers when'cement~ng wells.
Background Art [0U02] When drilling an oil or gas well, drilling :Quid having a prescribed density is used urin.g the drilling operation fox several purposes including, for example, 'balan ing a formation fluid pressure (which generally increases as the depth of a well ' creases) present in geola~gic formations that ate pe»,etrated by the wellbore_ 'tee 'lting fluid, or "drilling nnud,'° is typically pumped down a drillstring, tbxou a drill bit, and is retained to the surface though an annulus formed betwe n the drillstring and a wall of the wellbc~re. This process is knowxt as "circa ation" of the drilhing fluid.
j0003j If the density of the drilling fluid is excessive, the hydrostatic pressure e~erte by the drilling fluid on the formations can result in fractured formations and a exultant Ioss c~f drilling ft~eid into the "broken dawn" forertatians.
Loss of drillin fluid into the formation typically re$ults in "lost circulation"
(e.g., the Ions of a turn fluid communication path td the surface through, for example, the PATENT APPLiCA'x'IbN
ATfpRN~Y DQCXET N4. D998~bD2902 annulus) and eventually a pressure underbalence with respect to fluid pressure: Lost oixculation can result in uncantrohed discharge ox "blo vats" of pressurized formation, fluids to the surface because pressure control of th well has been lost. Fox' example, when dxilhn,~ fluid is lost iota the form tiara, the w~ellbore pressure rlrogs and pcrnrtits higher' pressure formatiota fluids to flaw into the wellbore in the form of a "lack." "tee lack may pmpa~ate to the s xfaee and result in a blowout that can damage z~ig equipment and injure ar kill rid personnel.
[tlQa4j These conditions may generally be avoided by appropriate selection of the densi of the drilling fluid used to drill the well. The density o~ the drilling fluid is us lly eozttrnlled by the addition of "weighting agents" i~n the form of, for exam 1e, particulate solids of heavy earth materials, such as barite. 'K' re weighting age~a are added to tire drilling zluid in a lmown ratio with respect to the fluid vole ' irr the wellbore to produce a aarefdlly regulated drilling fluid with a density.
[d0~~j During the drilling process, it is often neces$azy to periodically lower steel casing or well liners iota the wczzbore to line the walls thereof in order to maintain i of the wellbore. Moreover, the easing nr~ay be required to protect er forvaations frorxt the high wellbore pressures xequired to maintain fluid balance or cwer6alance witlx respect to formations near the bottom of the The casing, which is typically steel, must fit inszde the welzbore {04Q6j fter the casing is placed in the welzbore, an external casing annulus is forme between an outer surface of the casing and the wall of the well'bare. In order t prevent fluid comrnut~uicatic~n slang the external casing annulus, ail weh oemen is typically pumped into floe external casing annulus. Cemezttation of the casing in the welzbare is impoxkant because undesirable fluid cornrnunicatian PATENT APPL[~A'/ZQbf ATTORNEY T T30. 09'9$~p~?3 the bottom of the wellboxe and the surface through the external erasing can result in formation fluid leakage to the surface or to other subsurface ns, and can resuat in other types of well damage resulting in ~a loss of on pratential. Tl~e ail well eemexrt is placed ita the external casing annulus by pu ping a substanfiially fluid cement slurry dawn the casing, out of the bottom of the casing, and up into the external easing annulus.
[0007] During ttae cementing process, the cement slurry must completely displace the fling quid from the external oaring annulus because drilling fluid that is rat ed ntay prawide a path for ttie flow of formation fiuids up the external annulus after the cement has set. R~areover, slurries of oil well cemernt are ofitezt of chemically compatyble with canntnon drihir~g ~.ttids. For example, if the cem slu~y comes into diroct contact with the drilling fluid during fine displa ement process, the cement slurry and the drilling fluid rvay mix tagethez and fn a viscous material. ''V~Iher~ the'cemexrt slurry is pumped into the external casing annulus, the cement slurry may bypass the viscous material, thereby channels of viscous material that do not set up to form a solid, ably cement barrier to formation fluids. Accordingly, a ce~x5,ent "spacer"
fluid f often pumped into tl~e wellbore between the drilling fluid and the cement slurry to im~rmve the displacement of the drilling fluid and to prevent direct contac and mixing of the drilling fluid and the cement slurry.
[0008] Again, however, the density of such a cement spacer cannot exceed cextain lizxrits r the lost circulation condition will be encountered, and it cannot fall 'below other ~erfain lix~ts ox axt underbalanced condition will occur. Thus it is necessary to be le to co~.txol tl~e density of the spacer fluid used in cementing operations in a rn er similar to that used to control the density of dxilling fluid during drilling PATENT AhPWCATI01H
A,TTORN~Y DQCKET N0. 09982ro0~Qp2 [Ofl09] Prior art spacers are generally ade by mixing a suitable liquid base fluid with viscosifier which uaay be, for a ample, a soluble polymer or bentonite clay and weiglatin~ agent including, for xample, solid particles of barite or calcium Garb nate: The weighting agent rein also include low-density particles suc>a as hullo glass or cezamic spheres or f arced nitrogen, The mast camrnon spacez base aid is plain water. "Plain w ter" includes, for example, any souroe of chem cally suitable water that is readi y available for such applications;
incle~~ing fresh water, aeawater, saltwater, an brirxe. Alternatively, a suitable organic solve t may be used as the spacez base ftuzd. Glrganic solvents are open adv tageaus for use izt displacing of based drilling fluids. When used iz~
this mane; r, organic salvez~ts tray a1$o incl de viscosifiers and weighting agents.
[OOIt?] In prior art cement spacer fl ds, the viscosifier is used to support the panic es of weighting agent so as to p vent settling of the weighting agent dozing the p ping operation. A perfvxna, ce objective of the viscosifier. is bften to ,._ devel p °'gel strength" under static conditions to aid 'in the support of the weig g agent particles. Particle s tiling itt cement spacer fluids is usually eval ted in laboratories with settling is, similar to the Al?I free water test used far ce ent slurries. In the test, the v lame of free water, which accumulates o~n the t of the spacer under specifi conditiQns~ is determined. A common pzacti a is tar requite that the free water be below some maxixnutn voIurne.
[00~1J Therefore, it is desirable sa ba a $ cementing spacer That is designed to displ~ a drilling fluid in a weIlbore ate serve as a buffer between the drillitng fluid and a eruent slurry used to cement, fu exempts, casing in a wellbore.
ll~oreove~r, it is d sirable to have a ccmez~ting span that can be readily farmed at a v~ell site:
AT'I~RNEY bQ~XET ISO. C~h9B21Od2001 ~ s~A~E~s ~o~ m~:ov~~ vvE~~;
C~MENTA~'It7N
Cross-referet~~e to related applications This application is a continuation-in-part of U.S. Patent Application No.
Q9la~t,Q$3 led an February 26, X99$.
Background of invention Field of the Invention [UUDi] 'The invention relates generally to cementing spacers far use irr cementing wellb s. Mare specifically, the invention relates to the ><lse of Stokes haw cue ting spacers when'cement~ng wells.
Background Art [0U02] When drilling an oil or gas well, drilling :Quid having a prescribed density is used urin.g the drilling operation fox several purposes including, for example, 'balan ing a formation fluid pressure (which generally increases as the depth of a well ' creases) present in geola~gic formations that ate pe»,etrated by the wellbore_ 'tee 'lting fluid, or "drilling nnud,'° is typically pumped down a drillstring, tbxou a drill bit, and is retained to the surface though an annulus formed betwe n the drillstring and a wall of the wellbc~re. This process is knowxt as "circa ation" of the drilhing fluid.
j0003j If the density of the drilling fluid is excessive, the hydrostatic pressure e~erte by the drilling fluid on the formations can result in fractured formations and a exultant Ioss c~f drilling ft~eid into the "broken dawn" forertatians.
Loss of drillin fluid into the formation typically re$ults in "lost circulation"
(e.g., the Ions of a turn fluid communication path td the surface through, for example, the PATENT APPLiCA'x'IbN
ATfpRN~Y DQCXET N4. D998~bD2902 annulus) and eventually a pressure underbalence with respect to fluid pressure: Lost oixculation can result in uncantrohed discharge ox "blo vats" of pressurized formation, fluids to the surface because pressure control of th well has been lost. Fox' example, when dxilhn,~ fluid is lost iota the form tiara, the w~ellbore pressure rlrogs and pcrnrtits higher' pressure formatiota fluids to flaw into the wellbore in the form of a "lack." "tee lack may pmpa~ate to the s xfaee and result in a blowout that can damage z~ig equipment and injure ar kill rid personnel.
[tlQa4j These conditions may generally be avoided by appropriate selection of the densi of the drilling fluid used to drill the well. The density o~ the drilling fluid is us lly eozttrnlled by the addition of "weighting agents" i~n the form of, for exam 1e, particulate solids of heavy earth materials, such as barite. 'K' re weighting age~a are added to tire drilling zluid in a lmown ratio with respect to the fluid vole ' irr the wellbore to produce a aarefdlly regulated drilling fluid with a density.
[d0~~j During the drilling process, it is often neces$azy to periodically lower steel casing or well liners iota the wczzbore to line the walls thereof in order to maintain i of the wellbore. Moreover, the easing nr~ay be required to protect er forvaations frorxt the high wellbore pressures xequired to maintain fluid balance or cwer6alance witlx respect to formations near the bottom of the The casing, which is typically steel, must fit inszde the welzbore {04Q6j fter the casing is placed in the welzbore, an external casing annulus is forme between an outer surface of the casing and the wall of the well'bare. In order t prevent fluid comrnut~uicatic~n slang the external casing annulus, ail weh oemen is typically pumped into floe external casing annulus. Cemezttation of the casing in the welzbare is impoxkant because undesirable fluid cornrnunicatian PATENT APPL[~A'/ZQbf ATTORNEY T T30. 09'9$~p~?3 the bottom of the wellboxe and the surface through the external erasing can result in formation fluid leakage to the surface or to other subsurface ns, and can resuat in other types of well damage resulting in ~a loss of on pratential. Tl~e ail well eemexrt is placed ita the external casing annulus by pu ping a substanfiially fluid cement slurry dawn the casing, out of the bottom of the casing, and up into the external easing annulus.
[0007] During ttae cementing process, the cement slurry must completely displace the fling quid from the external oaring annulus because drilling fluid that is rat ed ntay prawide a path for ttie flow of formation fiuids up the external annulus after the cement has set. R~areover, slurries of oil well cemernt are ofitezt of chemically compatyble with canntnon drihir~g ~.ttids. For example, if the cem slu~y comes into diroct contact with the drilling fluid during fine displa ement process, the cement slurry and the drilling fluid rvay mix tagethez and fn a viscous material. ''V~Iher~ the'cemexrt slurry is pumped into the external casing annulus, the cement slurry may bypass the viscous material, thereby channels of viscous material that do not set up to form a solid, ably cement barrier to formation fluids. Accordingly, a ce~x5,ent "spacer"
fluid f often pumped into tl~e wellbore between the drilling fluid and the cement slurry to im~rmve the displacement of the drilling fluid and to prevent direct contac and mixing of the drilling fluid and the cement slurry.
[0008] Again, however, the density of such a cement spacer cannot exceed cextain lizxrits r the lost circulation condition will be encountered, and it cannot fall 'below other ~erfain lix~ts ox axt underbalanced condition will occur. Thus it is necessary to be le to co~.txol tl~e density of the spacer fluid used in cementing operations in a rn er similar to that used to control the density of dxilling fluid during drilling PATENT AhPWCATI01H
A,TTORN~Y DQCKET N0. 09982ro0~Qp2 [Ofl09] Prior art spacers are generally ade by mixing a suitable liquid base fluid with viscosifier which uaay be, for a ample, a soluble polymer or bentonite clay and weiglatin~ agent including, for xample, solid particles of barite or calcium Garb nate: The weighting agent rein also include low-density particles suc>a as hullo glass or cezamic spheres or f arced nitrogen, The mast camrnon spacez base aid is plain water. "Plain w ter" includes, for example, any souroe of chem cally suitable water that is readi y available for such applications;
incle~~ing fresh water, aeawater, saltwater, an brirxe. Alternatively, a suitable organic solve t may be used as the spacez base ftuzd. Glrganic solvents are open adv tageaus for use izt displacing of based drilling fluids. When used iz~
this mane; r, organic salvez~ts tray a1$o incl de viscosifiers and weighting agents.
[OOIt?] In prior art cement spacer fl ds, the viscosifier is used to support the panic es of weighting agent so as to p vent settling of the weighting agent dozing the p ping operation. A perfvxna, ce objective of the viscosifier. is bften to ,._ devel p °'gel strength" under static conditions to aid 'in the support of the weig g agent particles. Particle s tiling itt cement spacer fluids is usually eval ted in laboratories with settling is, similar to the Al?I free water test used far ce ent slurries. In the test, the v lame of free water, which accumulates o~n the t of the spacer under specifi conditiQns~ is determined. A common pzacti a is tar requite that the free water be below some maxixnutn voIurne.
[00~1J Therefore, it is desirable sa ba a $ cementing spacer That is designed to displ~ a drilling fluid in a weIlbore ate serve as a buffer between the drillitng fluid and a eruent slurry used to cement, fu exempts, casing in a wellbore.
ll~oreove~r, it is d sirable to have a ccmez~ting span that can be readily farmed at a v~ell site:
pA~'P.NT AP~LIGTION
Al'TDRNEY 150CKET Nfl: 0998042002 Summary of Inv~ttion [Odl2j A method of cementing a well using a cementing spacer. The method com rises puiriping a drilling fluid into a well and puuiping a oenrrenting Spacer into t a well to disglace the drilling ~ttid; wherein the ce;tnenting spacer comprises subst ntisl1y unviscosified water and a weighting agent. ~emcnt is then pumped into a well to displace the cementing spacer and the drilling fluid to complete the of the well.
[041] Other aspects and advantages o~ the invention wvill be appaxent from the folio ing de$ariptiQn and the appended claims.
Detailed Dese~Iptiora [001dj Ernbodinnents oaf the ixrventionl have bin developed ,txxom a study of particle settli calt:~ulations based on the 5tc~kes-Einstein equation. The particle settlzng caleul rions show that the sedimezttativn raze, or particle settling velocity, of partic ca o~ a weighting agent in a base fluid is relatively slow when compared to tlae de tlx of a typical well. For example, a total se~tirnentation distance o~ about 40 f t in a 4 hoax period was calculated for particles of a calcium carbonate agent in a water base fluid.
[~DiSj Accordingly, if a controlled density cemantix~g spacer comprising calcium carbo ate and water .(and substantially no viscosifier) is pumped into an external casing annulus in a substantially vertical, w611boxe, panicles of calcium, carbonate xx~ the ementlng spacer typically will settle no xn~ore than about 40 feet 1~y the time the c ent has set. This degree of settling will not cause any operational proble with respect to cexn.enting the well.
[~Ul6j In axt embodiment of the invention, the cen~Ienting spacer coxztprises a weigh 'ng agexit (such a$, for example, calcium carbonate, barite, ferrite, hematite, ~tc.) a d water. Note that as previously disclosed, "water" may include fresh pATHkIT APPLICATION
AT'rDRNE~f DOC~El' N0. 09p8214o20Q2 wat , salt water, seawater, brine, or any other chemically suitable sQUrce of water that '11 not adversely react with drilling mud ~ar the cement in the wellbore.
The came tang spacers descn'bed above are typically ~ referred to as "Stokes Law"
mix res. Tlxe resulting cementing spacers have numerous advantages discussed beta when compared to prior art spacers that ~ttse viscQSifiers to support the agent.
[007] ~ (~z~e form of the StQkes~Eixrsteix~, equation is shown below as Equation 1:
2g~'~ (dP - dr v = -_ .9v (I) whex in Y is a pazticle settling velocity (e~/seC), g is gravitational aCcelexatiQri (9$0 mlsecz), r is a particle radius (cm), ct~ is a particle density ($Iczri3), df is a fluid ensity (glcm3), ~n~i v is a fluid viscosity (poise).
[OOIg] Numerical solutia~ns of Equation 1, have been. determined for different types of p 'culate weighting agents (such as, for example; calcium caxbottate, bazxte, ferrit , hematite, etc.) and different particle diameters. Moreover; the solutions have een deterndned using water or organic solvents. The results show that, camp ed to a depth of a well (e.g., the overall height of a cement annulus from a casin bottom, ttr a well head) and to a length of a typical casing string, the velocity (or sedimentation rate) of particles of the weighting went is sub~tantiallv slow.
[001] TherefQxe, based on caleulatians performed using Equation 1, it has been date fined that cex~xenting spacers comprising neater aiad a .weighting age~tt lmwe a subs tially slow particle settling velocity so that they may be pumped into a well us~irtg typical rig operating techttiqt~es and do not require the addition of a visoos fiat (such as bentonite or viscosifyiatg polymers) to impede parCicle settle ant or otherwise affect the theology Qf the cementing spacer. A small of viscasifler may be present ixt the cerr~enting spaces as long as the L'.~'~'I' APPI~ICATtbhf AT't"bRNEY DOaC~'!' No. x/002602 amo t does not substantially affaet the rheoIogy of the cementing spacer (e.;~., $s .
long as the amount of visaosi~ex d4es riot substantially affect the settling:
,~
prop 'es t~~ the weighting agent). 'T'hese cementing spscexs do not adversely affeC cement slurries used to cement wells, and avoidance of the use of isco~ifiers may have several advantages, including:
~ ~ Cenaettting spacers are Iess expensive because they comprise fewer components.
~ ( Cementing spacers have predictable properCies resralting in less pilot testing and quality control reduiremetrts.
~ 'T$e reduction, or absence of gel strength devel~pxnent, cotnbinod with the settling motion of the cementing spacer particles, maintains hydrostatic pressure can the cement slurry as it sets and thereby provides a better seal through producing zones.
' ~ Cemert~k bond well lags are improved.
~ Cementing spacers have a subttantlally f~ewtonian rheolt~gy aztc~ experience turbulent flow at lower pumping rates and thereby improve ?the displacement of drilling fluid (in tl~e external c$sing annulus) by the cement slurry.
~ ~ Less mixing occurs at the interface between the turhu~'lent flow cementing spacer and the drilluag fluid, which also improves tt~e displacement of the drilling fluid.
[0~~4) While the cementing spacers comprise substantially unviscosi~ed water and a eighting agent, other non-viscosifying additives may be used as well.
For exam e, friction xedvtcing additives may be used with the invention. Friction Ici g additives may also serve to either r~tinimi~e or enhance solid packixxg of icl of the weighting agent.
PATEN'1 APPLi~AT'tON
A'1'FORN&Y b04KET NO. Opy82Np~pG~
[0021] Moreover, during extended settling conditions (e.g., settling oonr~itions that canti ue fc~r some time after the cement has set), particles of the weightiztg agent (vcrhi h may carnprxse, for cxanyle, barite) ~ the cementing spacer settle and may ~orm a "plug" (e.g., a "barite plug°') proximate the top of a cent column. ~'I'he plug onn,s an additional seal axed further prevents fluid transmission from the botto of the wellbore to the surface. The additional sealing pr4perrE;.es of the plug y be taseful, fc~r example, in, xlxeeting regulatory reqe~irements associated with, ~ fox example, cal oasiug pressure and/or microaxanttlar gas leakage (a that results from tl~e formation of a small mi~oannulus ox gap between the s cexxa~ent and the casing andJor the formation which may allow slow leakage c~f g to the surface).
(0022] Stokes Law calculations also apply to the "particle rise" of.partacles of low densi weighting agents that may be added to the oementying spacer. For exam 1e, the use of hollow glhss oar ceramic spheres, foamed >laitrogen, etc.;
to ' lower or reduce the density of the cementing spacer may also be used in eml~o invents of the invention. lFurkher, the cementing spactrs may be used tQ
expensive ail based drilling fluids from wells for Future muse.
[002] ~ While the invention has been described with respect to a limited number of emb invents, those skilled in the axt, having benefit of this disclgsure, will appre iate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the sca~pe c~f the should be limited only by the attached claims.
Al'TDRNEY 150CKET Nfl: 0998042002 Summary of Inv~ttion [Odl2j A method of cementing a well using a cementing spacer. The method com rises puiriping a drilling fluid into a well and puuiping a oenrrenting Spacer into t a well to disglace the drilling ~ttid; wherein the ce;tnenting spacer comprises subst ntisl1y unviscosified water and a weighting agent. ~emcnt is then pumped into a well to displace the cementing spacer and the drilling fluid to complete the of the well.
[041] Other aspects and advantages o~ the invention wvill be appaxent from the folio ing de$ariptiQn and the appended claims.
Detailed Dese~Iptiora [001dj Ernbodinnents oaf the ixrventionl have bin developed ,txxom a study of particle settli calt:~ulations based on the 5tc~kes-Einstein equation. The particle settlzng caleul rions show that the sedimezttativn raze, or particle settling velocity, of partic ca o~ a weighting agent in a base fluid is relatively slow when compared to tlae de tlx of a typical well. For example, a total se~tirnentation distance o~ about 40 f t in a 4 hoax period was calculated for particles of a calcium carbonate agent in a water base fluid.
[~DiSj Accordingly, if a controlled density cemantix~g spacer comprising calcium carbo ate and water .(and substantially no viscosifier) is pumped into an external casing annulus in a substantially vertical, w611boxe, panicles of calcium, carbonate xx~ the ementlng spacer typically will settle no xn~ore than about 40 feet 1~y the time the c ent has set. This degree of settling will not cause any operational proble with respect to cexn.enting the well.
[~Ul6j In axt embodiment of the invention, the cen~Ienting spacer coxztprises a weigh 'ng agexit (such a$, for example, calcium carbonate, barite, ferrite, hematite, ~tc.) a d water. Note that as previously disclosed, "water" may include fresh pATHkIT APPLICATION
AT'rDRNE~f DOC~El' N0. 09p8214o20Q2 wat , salt water, seawater, brine, or any other chemically suitable sQUrce of water that '11 not adversely react with drilling mud ~ar the cement in the wellbore.
The came tang spacers descn'bed above are typically ~ referred to as "Stokes Law"
mix res. Tlxe resulting cementing spacers have numerous advantages discussed beta when compared to prior art spacers that ~ttse viscQSifiers to support the agent.
[007] ~ (~z~e form of the StQkes~Eixrsteix~, equation is shown below as Equation 1:
2g~'~ (dP - dr v = -_ .9v (I) whex in Y is a pazticle settling velocity (e~/seC), g is gravitational aCcelexatiQri (9$0 mlsecz), r is a particle radius (cm), ct~ is a particle density ($Iczri3), df is a fluid ensity (glcm3), ~n~i v is a fluid viscosity (poise).
[OOIg] Numerical solutia~ns of Equation 1, have been. determined for different types of p 'culate weighting agents (such as, for example; calcium caxbottate, bazxte, ferrit , hematite, etc.) and different particle diameters. Moreover; the solutions have een deterndned using water or organic solvents. The results show that, camp ed to a depth of a well (e.g., the overall height of a cement annulus from a casin bottom, ttr a well head) and to a length of a typical casing string, the velocity (or sedimentation rate) of particles of the weighting went is sub~tantiallv slow.
[001] TherefQxe, based on caleulatians performed using Equation 1, it has been date fined that cex~xenting spacers comprising neater aiad a .weighting age~tt lmwe a subs tially slow particle settling velocity so that they may be pumped into a well us~irtg typical rig operating techttiqt~es and do not require the addition of a visoos fiat (such as bentonite or viscosifyiatg polymers) to impede parCicle settle ant or otherwise affect the theology Qf the cementing spacer. A small of viscasifler may be present ixt the cerr~enting spaces as long as the L'.~'~'I' APPI~ICATtbhf AT't"bRNEY DOaC~'!' No. x/002602 amo t does not substantially affaet the rheoIogy of the cementing spacer (e.;~., $s .
long as the amount of visaosi~ex d4es riot substantially affect the settling:
,~
prop 'es t~~ the weighting agent). 'T'hese cementing spscexs do not adversely affeC cement slurries used to cement wells, and avoidance of the use of isco~ifiers may have several advantages, including:
~ ~ Cenaettting spacers are Iess expensive because they comprise fewer components.
~ ( Cementing spacers have predictable properCies resralting in less pilot testing and quality control reduiremetrts.
~ 'T$e reduction, or absence of gel strength devel~pxnent, cotnbinod with the settling motion of the cementing spacer particles, maintains hydrostatic pressure can the cement slurry as it sets and thereby provides a better seal through producing zones.
' ~ Cemert~k bond well lags are improved.
~ Cementing spacers have a subttantlally f~ewtonian rheolt~gy aztc~ experience turbulent flow at lower pumping rates and thereby improve ?the displacement of drilling fluid (in tl~e external c$sing annulus) by the cement slurry.
~ ~ Less mixing occurs at the interface between the turhu~'lent flow cementing spacer and the drilluag fluid, which also improves tt~e displacement of the drilling fluid.
[0~~4) While the cementing spacers comprise substantially unviscosi~ed water and a eighting agent, other non-viscosifying additives may be used as well.
For exam e, friction xedvtcing additives may be used with the invention. Friction Ici g additives may also serve to either r~tinimi~e or enhance solid packixxg of icl of the weighting agent.
PATEN'1 APPLi~AT'tON
A'1'FORN&Y b04KET NO. Opy82Np~pG~
[0021] Moreover, during extended settling conditions (e.g., settling oonr~itions that canti ue fc~r some time after the cement has set), particles of the weightiztg agent (vcrhi h may carnprxse, for cxanyle, barite) ~ the cementing spacer settle and may ~orm a "plug" (e.g., a "barite plug°') proximate the top of a cent column. ~'I'he plug onn,s an additional seal axed further prevents fluid transmission from the botto of the wellbore to the surface. The additional sealing pr4perrE;.es of the plug y be taseful, fc~r example, in, xlxeeting regulatory reqe~irements associated with, ~ fox example, cal oasiug pressure and/or microaxanttlar gas leakage (a that results from tl~e formation of a small mi~oannulus ox gap between the s cexxa~ent and the casing andJor the formation which may allow slow leakage c~f g to the surface).
(0022] Stokes Law calculations also apply to the "particle rise" of.partacles of low densi weighting agents that may be added to the oementying spacer. For exam 1e, the use of hollow glhss oar ceramic spheres, foamed >laitrogen, etc.;
to ' lower or reduce the density of the cementing spacer may also be used in eml~o invents of the invention. lFurkher, the cementing spactrs may be used tQ
expensive ail based drilling fluids from wells for Future muse.
[002] ~ While the invention has been described with respect to a limited number of emb invents, those skilled in the axt, having benefit of this disclgsure, will appre iate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the sca~pe c~f the should be limited only by the attached claims.
Claims
Claims What is claimed is:
[c1] A method of cementing a well using a cementing spacer, the method comprising:
pumping a drilling fluid into a well;
pumping a cementing spacer into the well to displace the drilling fluid, the cementing spacer comprising substantially unviscosified water and a weighting agent; and pumping cement into the well to displace the cementing spacer and the drilling fluid and to thereby complete the cementing of the well.
[c2] The method of claim 1, wherein the weighting agent comprises barite.
[c3] The method of claim 1, wherein the weighting agent comprises calcium carbonate.
[c4] The method of claim 1, wherein the cementing spacer further comprises a friction reducing additive.
[c5] The method of claim 1, wherein the cementing spacer further comprises a low density weighting agent.
[c6] The method of claim 5, wherein the low density weighting agent comprises a selected volume of hallow glass spheres.
(c7] The method of claim 5, wherein the low density weighting agent comprises a selected volume of ceramic spheres.
[c8] The method of claim 5, wherein the low density weighting agent comprises a selected volume of foamed nitrogen.
[c1] A method of cementing a well using a cementing spacer, the method comprising:
pumping a drilling fluid into a well;
pumping a cementing spacer into the well to displace the drilling fluid, the cementing spacer comprising substantially unviscosified water and a weighting agent; and pumping cement into the well to displace the cementing spacer and the drilling fluid and to thereby complete the cementing of the well.
[c2] The method of claim 1, wherein the weighting agent comprises barite.
[c3] The method of claim 1, wherein the weighting agent comprises calcium carbonate.
[c4] The method of claim 1, wherein the cementing spacer further comprises a friction reducing additive.
[c5] The method of claim 1, wherein the cementing spacer further comprises a low density weighting agent.
[c6] The method of claim 5, wherein the low density weighting agent comprises a selected volume of hallow glass spheres.
(c7] The method of claim 5, wherein the low density weighting agent comprises a selected volume of ceramic spheres.
[c8] The method of claim 5, wherein the low density weighting agent comprises a selected volume of foamed nitrogen.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/818,109 | 2001-03-27 | ||
| US09/818,109 US20010022224A1 (en) | 1998-02-26 | 2001-03-27 | Cementing spacers for improved well cementation |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2377347A1 true CA2377347A1 (en) | 2002-09-27 |
| CA2377347C CA2377347C (en) | 2013-03-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2377347A Expired - Lifetime CA2377347C (en) | 2001-03-27 | 2002-03-22 | Cementing spacers for improved well cementation |
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| Country | Link |
|---|---|
| CA (1) | CA2377347C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103696730A (en) * | 2013-12-30 | 2014-04-02 | 新疆中核天山铀业有限公司 | Sludge leakage stopping method in drilling construction |
-
2002
- 2002-03-22 CA CA2377347A patent/CA2377347C/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103696730A (en) * | 2013-12-30 | 2014-04-02 | 新疆中核天山铀业有限公司 | Sludge leakage stopping method in drilling construction |
| CN103696730B (en) * | 2013-12-30 | 2016-05-18 | 新疆中核天山铀业有限公司 | Drilling construction spillage blocking method |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2377347C (en) | 2013-03-19 |
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